Physical quantity sensor, physical quantity sensor device, and inclinometer, inertia measurement device, structure monitoring device, and vehicle using physical quantity sensor device

ABSTRACT

A physical quantity sensor includes a base, at least two arms, a movable plate, a hinge, and a physical quantity measurement element. Four quadrants of the sensor are defined by first and second orthogonal lines. The first line passes through the center of the sensor and crosses the hinge. The second line extends along the hinge. Fixed regions of the sensor are located in the first and second quadrants. No fixed regions are located in at least one of the third and fourth quadrants. The third and fourth quadrants are closer to the base than the first and second quadrants in a plan view.

The present application is based on, and claims priority from JapaneseApplication Serial Number 2018-043532, filed Mar. 9, 2018, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a physical quantity sensor, a physicalquantity sensor device, and an inclinometer, an inertia measurementdevice, a structure monitoring device, a vehicle, and the like using thephysical quantity sensor device.

2. Related Art

JP-A-2000-65856 is an example of the related art.

In JP-A-2000-65856, an acceleration measurement device which includes abase made of a silicon semiconductor wafer, an upper electrode, and acantilever interposed between the base and the upper electrode andhaving a free end that can be bent around a fulcrum portion isdescribed.

However, in the acceleration measurement device described inJP-A-2000-65856, since the outer circumference of the accelerationmeasurement unit is all fixed, there is a problem that stress distortiondue to a difference in thermal expansion coefficients caused bydissimilar materials between a printed circuit board and theacceleration measurement device which occurs when the accelerationmeasurement device is mounted on the printed circuit board istransmitted to the physical quantity measurement element fixed to acontainer of a device and a rigid portion through the container.

SUMMARY

An advantage of some aspects of the present disclosure is to solve atleast a part of the problems described above, and the present disclosurecan be implemented as the following aspects.

(1) An aspect of the present disclosure relates to a physical quantitysensor which includes a base, a movable portion coupled to the base, afirst arm portion connected to the base, a second arm portion connectedto the base, and a physical quantity measurement element that isattached to the base and the movable portion and measures a physicalquantity caused by stress generated in a direction connecting the baseand the movable portion, and in which the first arm portion is disposedin a first region on one side in a second direction orthogonal to afirst direction connecting the base and the movable portion and isprovided with a fixed region which is provided closer to the movableportion side than to the base side, the second arm portion is disposedin a second region on the other side in the second direction orthogonalto the first direction and is provided with a fixed region which isprovided in at least one region of the movable portion side and the baseside, and a fixed region is not disposed in at least one of a thirdregion positioned on the base side of the first region and a fourthregion positioned on the base side of the second region.

(2) In the physical quantity sensor according to the aspect (1) of thepresent disclosure, the fixed region of the second arm portion may bedisposed on the base side.

(3) In the physical quantity sensor according to the aspect (1) of thepresent disclosure, the fixed region of the second arm portion may bedisposed on the movable portion side.

(4) In the physical quantity sensor according to the aspect (3) of thepresent disclosure, a third arm portion connected to the base may befurther included, and the third arm portion may be provided with a fixedregion provided in any one of the third region and the fourth region inthe third arm portion.

(5) In the physical quantity sensor according to the aspect (1) of thepresent disclosure, a fourth arm portion connected to the base may befurther included, and the fourth arm portion may be provided with aprotrusion on a surface opposite to a surface to which the physicalquantity measurement element is attached in at least one region wherethe fixed region is not disposed among the first to fourth regions.

(6) In the physical quantity sensor according to the aspect (1) of thepresent disclosure, a groove in which an adhesive is filled may beprovided in the fixed region.

(7) In the physical quantity sensor according to the aspect (1) of thepresent disclosure, the base and the movable portion may be coupledthrough a constricted portion.

(8) Another aspect of the present disclosure relates to a physicalquantity sensor device which includes the physical quantity sensoraccording to the aspect (1) of the present disclosure, and a base onwhich the physical quantity sensor is mounted, and in which the fixedregion is attached to the base.

(9) In the physical quantity sensor device according to the aspect (8)of the present disclosure, a circuit board may be further included,three physical quantity sensors may be provided, and the three physicalquantity sensors may be mounted on the circuit board so that each ofmeasurement axes of the three physical quantity sensors is aligned witheach of three axes orthogonal to each other.

(10) In the physical quantity sensor device according to the aspect (8)or (9) of the present disclosure, the physical quantity may beacceleration.

(11) Another aspect of the present disclosure relates to an inclinometerwhich includes the physical quantity sensor device according to (10) anda calculator that calculates an inclination angle of a structure basedon an output signal from the physical quantity sensor device attached tothe structure.

(12) Another aspect of the present disclosure relates to a structuremonitoring device which includes the physical quantity sensor deviceaccording to (10), a receiver that receives a measurement signal fromthe physical quantity sensor device attached to a structure, and acalculator that calculates an inclination angle of the structure basedon a signal output from the receiver.

(13) Another aspect of the present disclosure relates to a vehicle whichincludes the physical quantity sensor device according to (10) and acontroller that controls at least one of acceleration, braking, andsteering based on a measurement signal detected by the physical quantitysensor device, and in which execution or non-execution of an automaticoperation is switched according to a change in a measurement signal fromthe physical quantity sensor device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a sensor portion of a physical quantitysensor according to an embodiment of the present disclosure.

FIG. 2 is a cross-sectional view of a physical quantity sensor deviceaccording to an embodiment of the present disclosure.

FIG. 3 is an exploded perspective view of a triaxial physical quantitysensor device according to an embodiment of the present disclosure.

FIG. 4 is an exploded perspective view illustrating another example ofthe triaxial physical quantity sensor device.

FIG. 5 is a plan view illustrating a disposition of fixed regionsaccording to a first embodiment of the present disclosure.

FIG. 6 is a plan view illustrating a disposition of fixed regionsaccording to a second embodiment of the present disclosure.

FIG. 7 is a plan view showing a disposition of fixed regions accordingto a third embodiment of the present disclosure.

FIG. 8 is a characteristic diagram illustrating temperaturecharacteristics of the physical quantity sensor device.

FIG. 9 is a view illustrating a protrusion provided on a third armportion.

FIG. 10 is a view illustrating another example of joining of an armportion and a base.

FIG. 11 is a view illustrating still another example of joining of thearm portion and the base.

FIG. 12 is a side view illustrating an inclinometer including thephysical quantity sensor device.

FIG. 13 is a block diagram of the inclinometer including the physicalquantity sensor device.

FIG. 14 is a coordinate view for explaining an example of calculation ofan inclination angle.

FIG. 15 is a side view illustrating an inertia measurement deviceincluding the physical quantity sensor device.

FIG. 16 is a block diagram of the inertia measurement device.

FIG. 17 is a schematic view illustrating a structure monitoring deviceincluding the physical quantity sensor device.

FIG. 18 is a block diagram of the structure monitoring device.

FIG. 19 is a schematic view illustrating a vehicle including thephysical quantity sensor device.

FIG. 20 is a block diagram of the vehicle.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail. The embodiment described below does not undulylimit scope of the present disclosure described in the appended claims,and not all of the configurations described in the embodiment arenecessarily indispensable components of the present disclosure.

1. Overview of Physical Quantity Sensor and Physical Quantity SensorDevice

FIG. 1 illustrates a physical quantity sensor 10. The physical quantitysensor 10 includes a base 20, at least two, for example three armsincluding a first arm portion 31 (first arm), a second arm portion 32(second arm), and a third arm portion 33 (third arm), and a movableportion 40 (movable plate), a constricted portion 50 (living hinge), anda physical quantity measurement element 60 (oscillator/sensor).

The first arm portion 31, the second arm portion 32, and the third armportion 33 have proximal ends connected to the base 20, and preferably,a fixed region 31A, a fixed region 32A, and a fixed region 33A areprovided on the free ends, respectively. The constricted portion 50 as aconnection portion is disposed between the base 20 and the movableportion 40, and connects the base 20 and the movable portion 40. Thephysical quantity measurement element 60 is constituted by, for example,a double-ended tuning fork type quartz crystal oscillator, and measures,for example, acceleration and pressure as a physical quantity. Thephysical quantity measurement element 60 is disposed (spans) across theconstricted portion 50 in a plan view when seen in the thicknessdirection of the base 20 and is attached to the base 20 and the movableportion 40 through a joining portion 61 (fastener, see FIG. 2) such asan adhesive. Further, a weight (mass portion) 70 made of, for example,metal (SUS, copper, and the like) can be disposed on the free end sideof the movable portion 40 which is a cantilever with the constrictedportion 50 as a fulcrum. The weight 70 is not limited to being providedon the front surface side of the movable portion 40 as illustrated inFIG. 1, but can also be provided on the back surface side of the movableportion 40 (see FIG. 2). As illustrated in FIG. 1 and FIG. 2, the weight70 is attached to the movable portion 40 by a joining portion 71(fastener) such as an adhesive. Although the weight 70 illustrated inFIG. 1 moves up and down together with the movable portion 40, both endportions 70A and 70B (ends) of the weight 70 function as stoppers forpreventing excessive amplitude by making contact with the arm portion 31and the arm portion 32 illustrated in FIG. 1.

Stress is generated in the physical quantity measurement element 60attached to the base 20 and the movable portion 40 by displacing themovable portion 40 with the constricted portion 50 as a fulcrumaccording to the physical quantities such as acceleration and pressure.A vibration frequency (resonance frequency) of the physical quantitymeasurement element 60 changes according to the stress applied to thephysical quantity measurement element 60. Based on the change in thevibration frequency, the physical quantity can be detected.

FIG. 2 is a cross-sectional view illustrating a physical quantity sensordevice 100 in which the physical quantity sensor 10 of FIG. 1 isincorporated. The physical quantity sensor device 100 includes a base110 on which the physical quantity sensor 10 is mounted. In thisembodiment, the base 110 is configured as a package base including abottom wall 110A and side walls 110B. The base 110, together with a lid120, forms a package for accommodating the physical quantity sensor 10therein. The lid 120 is joined to an opening end of the base 110 throughan adhesive 121.

On the bottom wall 110A of the base 110, a step portion 112 one stephigher than an inner surface 110A1 of the bottom wall 110A is providedalong, for example, three side walls 110B of four side walls 110B. Thestep portion 112 may protrude from the inner surface of the side wall110B or may be integral with or separate from the base 110, but is apart constituting the base 110. As illustrated in FIG. 2, the physicalquantity sensor 10 is fixed to the step portion 112 with an adhesive113. Here, as the adhesive 113, it is preferable to use a resin-based(for example, epoxy resin) adhesive having a high elastic modulus. Sincean adhesive such as low melting point glass is hard, the adhesive cannotabsorb stress distortion generated at the time of joining and adverselyaffects the physical quantity measurement element 60. The positions ofthe fixed regions 31A to 33A where the physical quantity sensor 10 isfixed to the step portion 112 will be described later with reference toFIG. 1 and FIGS. 5 to 7.

In this embodiment, as illustrated in FIG. 1, the physical quantitymeasurement element 60 can be connected to electrodes (for example, goldelectrodes) formed in the step portion 112 by bonding wires 62 and 62.In this case, it is unnecessary to form an electrode pattern on the base20. The electrode pattern also provided on the base 20 may be connectedto the electrodes formed on the step portion 112 of the base 110 througha conductive adhesive without adopting the bonding wires 62 and 62.

On the outer surface (surface opposite to the inner surface 110A1) 110A2of the bottom wall 110A of the base 110, an external terminal 114 usedfor mounting to an element on an electronic circuit board 210Aillustrated in FIG. 3 is provided. The external terminal 114 iselectrically connected to the physical quantity measurement element 60through a wiring, an electrode, or the like (not illustrated).

For example, a sealing portion 115 for sealing the inside (cavity) 130of a package formed by the base 110 and the lid 120 is provided on thebottom wall 110A. The sealing portion 115 is provided in a through-hole116 formed in the base 110. The sealing portion 115 is provided bydisposing a sealing material in the through-hole 116, heating andmelting the sealing material, and solidifying the sealing material. Thesealing portion 115 is provided to hermetically seal the inside of thepackage.

FIG. 3 is an exploded perspective view of a triaxial physical quantitysensor device 200A including three uniaxial physical quantity sensordevices 100. In FIG. 3 three physical quantity sensor devices 100 aremounted on the electronic circuit board 210A. In the three uniaxialphysical quantity sensor devices 100, measurement axes are providedalong three orthogonal axes to detect physical quantities of the threeaxes. The circuit board 210A is electrically connected to a connectorboard 220A. The circuit board 210A and the connector board 220A areaccommodated in a package formed by a package base 230A and a lid 240A.

FIG. 4 illustrates a triaxial physical quantity sensor device 200B whichis different from that illustrated in FIG. 3. In FIG. 3, the circuitboard 210A and the connector board 220A are juxtaposed on the sameplane, but in FIG. 4, a circuit board 210B and a connector board 220Bare juxtaposed in the vertical direction. Also in FIG. 4, the circuitboard 210B and the connector board 220B are accommodated and held in apackage formed by a package base 230B and a lid 240B.

2. Fixed Position of Physical Quantity Sensor with Respect to Base

2.1. First Embodiment

In FIG. 1, the three arm portions 31 to 33, in which fixed regions 31Ato 33A which are secured to the step portion 112 provided in a part ofthe base 110 are respectively provided, are illustrated. In FIG. 1,positions at which the fixed regions 31A to 33A are fixed to the stepportion 112 are illustrated in a plan view. In this embodiment, thefixed regions 31A to 33A on the back surfaces (surface opposite to thesurface on a side on which the physical quantity measurement element 60is fixed) of the three arm portions 31 to 33 illustrated in FIG. 1 arefixed to the step portion 112.

Here, the positions of the fixed regions 31A to 33A illustrated in FIG.1 will be described with reference to FIG. 5 when the physical quantitysensor 10 is viewed in a plan view. In FIG. 5, a straight line L1(bi-sector) passing through the center of the physical quantitymeasurement element 60 along a direction that crosses the constrictedportion 50 is referred to as a first straight line. Two regionspartitioned by the first straight line L1 are referred to as a first(lateral) region A1 and a second (lateral) region A2. In FIG. 5, theleft side of the first straight line L1 is set as the first region A1,and the right side thereof is set as the second region. However, in FIG.5, the right side of the first straight line L1 may be referred to as afirst region and the left side thereof may be referred to as a secondregion. In this embodiment, the fixed region 31A is disposed in thefirst region A1 and the fixed regions 32A and 33A are disposed in thesecond region A2.

In FIG. 5, a straight line L2 (pivot axis) passing through theconstricted portion 50 and orthogonal to the first straight line L1 isreferred to as a second straight line. Four regions B11, B12, B21, andB22 that respectively belong to regions of a first quadrant to a fourthquadrant are partitioned by the first straight line L1 (first direction)and the second straight line L2 (second direction) of the two orthogonalaxes. Further, a side close to a C1 side illustrated in FIG. 5 from thesecond straight line L2 is referred to as the “base side” of thephysical quantity measurement element 60. Similarly, a side close to aside C2 illustrated in FIG. 5 from the second straight line L2 isreferred to as the “movable portion side”. A region B22 which isdisposed in the first region A1 and closer to the base side (C1 side)than to the second straight line L2 is referred to as a third regionB22. A region B12 which is disposed in the second region A2 and closerto the base side (C1 side) than to the second straight line L2 isreferred to as a fourth region B12.

In the embodiment illustrated in FIG. 5, the fixed region 31A isdisposed in the region B21 on the movable portion side (C2 side) of thefirst region A1. The fixed region 32A is disposed in the region B11 onthe movable portion side (C2 side) of the second region A2. The fixedregion 33A is disposed in the region (fourth region) B12 on the baseside (C1 side) of the second region A2. That is, in the embodimentillustrated in FIG. 5, neither the fixed region 31A nor the fixed region32A is provided in the third region B22 or the fourth region B12, and inFIG. 5, no fixed region is provided in the third region B22.

Here, in this embodiment, the reason why the first to third arm portions31 to 33 connected to the base 20 are provided instead of fixing theentire outer circumference as in JP-A-2000-65856 discussed above is thata degree of freedom of deformation is given to locally fixed armportions 31 to 33 and stress is concentrated on the first to third armportions 31 to 33 to absorb stress distortion by deformation of thefirst to third arm portions 31 to 33. When stress distortion is absorbedby deformation of the first to third arm portions 31 to 33, it ispossible to reduce or prevent transmission of stress distortion to thephysical quantity measurement element 60. The physical quantitymeasurement element 60 measures a physical quantity by using, forexample, a change in physical quantity measurement information generatedin the physical quantity measurement element 60 due to a stress causedby acceleration. When a stress distortion caused by a source to beavoided originally (a mechanical overload at the time of manufacture ora difference in thermal expansion coefficients between dissimilarmaterials connected to each other) acts on the physical quantitymeasurement element 60, as a result of action of stress distortion onthe physical quantity detecting element 60, physical quantitymeasurement information also changes and the measurement accuracydeteriorates. In contrast, in this embodiment, the measurement accuracycan be improved.

In this embodiment, in addition to adopting local fixation using the armportions that deform without fixing around the entire circumference, theadverse influence of stress distortion is further reduced by limitingthe positions of the locally fixed regions. In FIG. 5, a fixed region isnot provided in the region B22 of the fourth quadrant. With thisconfiguration, the degrees of freedom of deformation of the first tothird arm portions 31 to 33 are further increased as compared with thecase where the first to third arm portions 31 to 33 are locally fixed inthe entire regions B11, B12, B21, and B 22 of the first to fourthquadrants, thereby capable of absorbing stress distortion. Inparticular, since the fixed region is not provided in the third regionB22 which is the base side (C1 side) of the second straight line L2, thebase 20 is also easily deformed, and it is possible to effectivelyreduce the action of stress distortion on the physical quantitymeasurement element 60. For this reason, the fixed region 33Aillustrated in FIG. 5 may be provided in the third region B22 instead ofthe fourth region B12. In either case, the fixed region is not disposedin one of the third region B22 or the fourth region B12.

2.2. Second Embodiment

FIG. 6 illustrates a second embodiment including fixed regions 31A and33A illustrated in FIG. 5 but not the fixed region 32A. That is, thefixed regions illustrated in FIG. 6 are configured with the fixed region(referred to as the first fixed region) 31A disposed in the region(referred to as a fifth region) B21 positioned in the first region A1 tobe closer to the movable portion side (C2 side) than to the secondstraight line L2 and the fixed region (referred to as a second fixedregion) 33A disposed in the region (referred to as a sixth region) B12positioned in the second region A2 to be closer to the base side (C1side) than to the second straight line L2. By doing so, a supportstructure is changed from a three-point support illustrated in FIG. 5 toa two-point support, and the degrees of freedom of deformation of thearm portions 31 and 33 and the base 20 are further increased. However,since the first and second fixed regions 31A and 33A are provided in theregions B12 and B21 of the second and third quadrants positioned atdiagonally opposed positions, it is possible to stably support thephysical quantity sensor 10. For this reason, even if the first andsecond fixed regions are instead provided in the regions B11 and B22 ofthe first and fourth quadrants at diagonally opposed positions, the sameeffect can be obtained.

2.3. Third Embodiment

FIG. 7 illustrates a third embodiment including the fixed regions 31Aand 32A illustrated in FIG. 5 but not the fixed region 33A. That is, thefixed region illustrated in FIG. 7 is configured with the fixed region(referred to as the first fixed region) 31A disposed in the region(referred to as a fifth region) B21 positioned in the first region A1 tobe closer to the movable portion side (C2 side) than to the secondstraight line L2 and the fixed region (referred to as the second fixedregion) 32A disposed in the region (referred to as a sixth region) B11positioned in the second region A2 to be closer to the movable portionside (C2 side) than to the second straight line L2. By doing so, asupport structure is changed from a three-point support illustrated inFIG. 5 to a two-point support, and the degrees of freedom of deformationof the arm portions 31 and 32 are further increased. In this case, sincethe first and second fixed regions 31A and 32A are disposed in the firstregion A1 and the second region A2, it is possible to stably support thephysical quantity sensor 10.

3. Evaluation of First Embodiment, Second Embodiment, and ThirdEmbodiment

In order to evaluate whether or not stress distortion due to anunintended cause acted on the physical quantity measurement element 60,as illustrated in the following Table 1, a change in temperaturecharacteristics of the physical quantity measurement element 60 (changein position of the average peak in the temperature characteristics),reproducibility, and hysteresis were evaluated. Here, in comparativeexamples 1 and 2 in the following Table 1, fixed regions are disposed inthe four regions B11, B12, B21, and B22 in the first to fourth quadrantsillustrated in FIGS. 5 to 7. In the comparative example 2, the armportion is made thicker than that in the comparative example 1 toincrease rigidity of the arm portion. In the comparative example 3 inthe Table 1, fixed regions are disposed at two places (i.e., the regionsB12 and B22 positioned in the second and fourth quadrants illustrated inFIGS. 5 to 7). Each of the comparative examples 1 to 3 is different fromthe first to third embodiments of the present disclosure in that thecomparative examples 1 to 3 have fixed regions in two regions B12 andB22 positioned closer to the base side (C1 side) than to the secondstraight line L2, respectively.

TABLE 1 Average peak Reproducibility Hysteresis temperature crystaloscillator itself 0.1 mG 0.1 mG 25.2° C. Comparative Example 1 0.8 mG0.5 mG  5.3° C. Comparative Example 2 1.6 mG 4.5 mG −31.4° C. Comparative Example 3 2.1 mG 1.2 mG −38.3° C.  Third Embodiment 0.1 mG0.2 mG 25.3° C. Second embodiment 0.2 mG 0.4 mG 25.3° C. FirstEmbodiment −0.1 mG  −0.2 mG  23.2° C.

3.1. Temperature Characteristics

FIG. 8 illustrates the temperature characteristics of a quartz crystaloscillator which is an example of the physical quantity measurementelement 60. In FIG. 8, the vertical axis represents a frequency changeamount (df/f), and the horizontal axis represents a temperature (° C.).A characteristic K0 illustrates intrinsic temperature characteristics ofthe quartz crystal oscillator on which no stress distortion is acted.The characteristic K0 is the intrinsic temperature characteristics basedon the Young's modulus of the quartz crystal, and the peak temperatureis 25.2° C. (see also Table 1).

The characteristics K1 and K2 in FIG. 8 are characteristics of thecomparative examples 1 and 2 in Table 1. When a stress acts on thequartz crystal oscillator due to the influence of thermal expansioncoefficient difference or the like is applied, temperaturecharacteristics K1 and K2 in FIG. 8 are inclined and the peaktemperature is shifted in the minus direction. Since the characteristicK2 has a higher rigidity of the arm portion than the characteristic K1and the effect of absorbing the stress distortion is small, inclinationbecomes larger.

As illustrated in Table 1, it can be seen that the average peaktemperature of the comparative examples 1 to 3 is shifted to the minusside by more than 25.2° C. which is the peak temperature intrinsic toquartz crystal. On the other hand, in the first to third embodiments ofthe present disclosure, the average peak temperature is maintained inthe vicinity of the peak temperature 25.2° C. intrinsic to quartzcrystal. With this configuration, unnecessary stress acting on thephysical quantity measurement element 60 is reduced in the first tothird embodiments of the present disclosure in which a fixed region isnot included in at least one of the regions B12 and B22 positionedcloser to the base side (C1 side) than to the second straight line L2.

3.2. Reproducibility

The “reproducibility” illustrated in Table 1 represents how much thephysical quantity (acceleration in Table 1) detected by the physicalquantity measurement element 60 deviates between the start point and theend point when the temperature is raised or lowered is by the magnitude(mG) of deviated acceleration. The larger the absolute value shifted inthe positive direction or the negative direction is, the worse thereproducibility is illustrated. It can be seen that the first to thirdembodiments of the present disclosure in which temperature drift issmall are more excellent in terms of reproducibility than thecomparative examples 1 to 3 in which temperature drift is high.

3.3. Hysteresis

The “Hysteresis” illustrated in Table 1 represents the maximum value ofthe deviation of the physical quantity (acceleration in Table 1)measured by the physical quantity measurement element 60 when thetemperature is raised or lowered by the magnitude (mG) of deviatedacceleration. It can be seen that the first to third embodiments of thepresent disclosure in which temperature drift is small are moreexcellent in terms of hysteresis than the comparative examples 1 to 3 inwhich the temperature drift is large.

Other evaluation items other than the above-mentioned temperaturecharacteristics, reproducibility, and hysteresis were also examined.

3.4. Stability During Assembly

As illustrated FIG. 5, if there are three fixed regions 31A to 33A,since three points are supported by the step portion 112 of the base 110illustrated in FIG. 2, the physical quantity sensor 10 is stably placedon the step portion 112. On the other hand, in FIG. 6 and FIG. 7, sincethe two points are supported by the two fixed regions, stability at thetime of being placed on the step portion 112 and assembled is poor.Accordingly, in the embodiments of FIGS. 5 to 7, particularly theembodiments of FIGS. 6 and 7, it is possible to further provide a thirdarm portion 34 connected to the base 20 as illustrated in FIG. 9. Thethird arm portion 34 may include a protrusion 34A formed on a surfaceopposite to the surface to which the physical quantity measurementelement 60 is connected in at least one region among the four regionsB11, B12, B21, and B22 in which the fixed region is not disposed in aplan view. The height H of the protrusion 34A is substantially equal tothe thickness T of the joining portion (adhesive) 113 illustrated inFIG. 2. With this configuration, when the physical quantity sensor 10 isplaced on the base 110, the physical quantity sensor 10 is supported atthree points by the two fixed regions and abutting contact of theprotrusion 34A, and the stability during assembly is improved. However,the protrusion 34A is not joined to the step portion 112.

3.5. Impact Resistance

Depending on the use of the physical quantity sensor 10, impactresistance is also required. To increase the impact resistance, it isconceivable to increase the rigidity of the arm portion. As can be seenfrom the deterioration of the characteristics of the comparative example2 in which the rigidity of the arm portion is increased as compared withthe comparative example 1, securing the impact resistance and improvingthe temperature characteristic of the physical quantity sensor 10 have atradeoff with each other. Even if the rigidity of the arm portion isincreased to secure the impact resistance in the first to thirdembodiments of the present disclosure, deterioration of the temperaturecharacteristic of the physical quantity sensor 10 can be suppressed incomparison with the comparative examples 1 to 3.

As described above, in the first to third embodiments of the presentdisclosure, in the physical quantity sensor 10 including the base 20illustrated in FIG. 1, at least two arm portions (any one of 31A to 33A,31A and 32A, and 31A and 33A), the movable portion 40, the constrictedportion 50, and the physical quantity measurement element 60, the fixedregions (31A to 33A) illustrated in FIGS. 5 to 7 are disposed in thefirst region A1 and the second region A2 partitioned by the firststraight line L1 passing through the center of the physical quantitymeasurement element 60 along the direction crossing the constrictedportion 50 in a plan view, and are not disposed in at least one of thethird region B22 positioned in the first region A1 to be closer to thebase side (C1 side) than to the second straight line L2 and the fourthregion B12 positioned in the second region A2 to be closer to the baseside (C1 side) than to the second straight line L2 among the fourregions (B1, B12, B21, and B22) partitioned by the first straight lineL1 and the second straight line L2 passing over the constricted portion50 and orthogonal to the first straight line L1 in a plan view. Withthis configuration, the stress distortion caused by a source to beavoided originally (a mechanical overload at the time of manufacture ora difference in thermal expansion coefficient between dissimilarmaterials connected to each other) acts on the physical quantitymeasurement element 60 is reduced. Thus, it is possible to provide thephysical quantity sensor 10 excellent in reproducibility, hysteresis,temperature characteristics (shift of the average peak temperature)illustrated in Table 1 and the physical quantity sensor device 100having the physical quantity sensor 10 mounted on the base 110.

3.6. Joining of Physical Quantity Sensor and Base

In this embodiment, the physical quantity measurement element 60 of thephysical quantity sensor 10 can be connected to the electrode formed inthe step portion 112 by the bonding wires 62 and 62 illustrated inFIG. 1. This is because there is no possibility that the bonding wires62 and 62 are disconnected since the stress distortion described abovedoes not act on the physical quantity measurement element 60. By usingthe bonding wires 62 and 62, there is no need to connect an electrodepattern provided on the base 20 to a gold electrode on the step portion112 through a conductive adhesive. Adhesion between the gold electrodeand the conductive adhesive is easy to peel off because theintermolecular force decreases at high temperature, but such an adverseeffect can be eliminated when bonding wires 62 and 62 are used.

The first to third fixed regions 31A to 33A of the physical quantitysensor 10 and the step portion 112 of the base 110 are joined with anadhesive, preferably a resin-based adhesive 113, as described above. Inthis case, the joining illustrated in FIG. 10 or FIG. 11 can be adopted.

In FIG. 10, in the first to third arm portions 31 to 33, for example,quartz crystal which is a base material is half-etched, and thethickness of the free end is made thin. In FIG. 11, in the first tothird arm portions 31 to 33, for example, quartz crystal which is a basematerial is locally etched through a mask or the like to form a grooveat the free end. In FIGS. 10 and 11, the resin-based adhesive 113 isfilled in the gap between the free ends of the first to third armportions 31 to 33, the step portion 112, and side walls 110B. With thisconfiguration, an adhesion area (surface area) is increased and strengthis increased. In FIG. 10, furthermore, when the physical quantity sensor10 is mounted on the base 110, since rotation and misalignment areunlikely to occur, assembly workability is improved.

4. Apparatus Using Physical Quantity Sensor Device

Hereinafter, an apparatus using the physical quantity sensor devicehaving the configuration described above will be described withreference to FIGS. 12 to 20.

4.1. Inclinometer

FIG. 12 is a diagram illustrating a configuration example of theinclinometer, and is a side view illustrating a partial cross section.

An inclinometer 300 is a device that outputs a signal corresponding toan inclination angle of a position where the inclinometer 300 isinstalled. Specifically, the inclinometer 300 includes a physicalquantity sensor device 310 having the structure of the physical quantitysensor device 200A (200B) of the first embodiment, a calculator 330 forcalculating the inclination angle based on the output signal of thephysical quantity sensor device 310, and an external output terminal 332for outputting a signal according to the inclination angle calculated bythe calculator 210 to the outside in an inner space defined by an undercase 301 and an upper case 302. The inclinometer 300 may appropriatelyinclude other elements. For example, a built-in battery, a power supplycircuit, a wireless device, and the like.

The inclination calculator 330 is a circuit that computes theinclination angle from the output signal of the physical quantity sensordevice 310 and outputs a signal corresponding to the inclination angleand can be realized by, for example, a general purpose integratedcircuit (IC), a field programmable gate array (FPGA), or the like.

From the physical quantity sensor device 310, for example, accelerationsin directions of the x-axis, y-axis, and z-axis which are threeorthogonal axes are output. The inclinometer 300 measures inclinationangles (angles between the x-axis, y-axis, and z-axis and the horizontalplane) of the x-axis, y-axis, and z-axis from accelerations in thex-axis, y-axis, and z-axis directions. For example, the inclinometer 300may be mounted on the floor surface near the center of gravity of a shipso that the x-axis faces the bow direction of the ship, the y-axis facesthe port side of the ship, and the z-axis faces the floor surfacevertical direction.

As illustrated in FIG. 13, a corrector 320 (processor) can be includedbetween the physical quantity sensor device 310 and the inclinationcalculator 330. The corrector 320 corrects accelerations in the x-axis,y-axis, and z-axis directions output from the physical quantity sensordevice 310. For example, the corrector 320 performs alignment correctionof accelerations in the x-axis, y-axis, and z-axis directions outputfrom the physical quantity sensor device 310, offset correction,temperature drift correction, and the like. The corrector 320 may beomitted when the alignment of acceleration output from the physicalquantity sensor device 310, the offset, the temperature drift, and thelike are small.

The inclination calculator 330 (corresponding to the calculatoraccording to the present disclosure, e.g., a circuit, processor or CPU)can calculate the inclination of each axis with respect to thehorizontal plane based on the accelerations in the x-axis, y-axis, andz-axis directions corrected by the corrector 320.

FIG. 14 is a view for explaining a calculation example of theinclination angle. “x′” illustrated in FIG. 14 indicates an axisparallel to the horizontal direction, and “z′” indicates an axisparallel to the direction of gravity (vertical). “x” indicates thex-axis of the physical quantity sensor device 310. “z” indicates thez-axis of the physical quantity sensor device 310. It is assumed thatthe “y-axis” of the physical quantity sensor device 310 faces the backside of the page. The direction of gravitational acceleration is upwardin FIG. 14.

As illustrated in FIG. 14, the x-axis of the physical quantity sensordevice 310 is assumed to be inclined at an angle “θ_(x)” about they-axis as a rotation axis. In this case, it is assumed that theacceleration (gravitational acceleration component) in the x-axisdirection output from the acceleration sensor 11 is “a_(x)”, thefollowing expression (1) is established.

$\begin{matrix}{{\sin \mspace{11mu} \theta_{x}} = \frac{a_{x}}{1G}} & (1)\end{matrix}$

“1G” expressed in the expression (1) is gravitational acceleration and“1G=9.80665 m/s²”.

From the expression (1), inclination “θ_(x)” of the x-axis with respectto the horizontal direction is expressed by the following expression(2).

$\begin{matrix}{\theta_{x} = {\sin^{- 1}\frac{a_{x}}{1G}}} & (2)\end{matrix}$

Similarly, inclinations “θ_(y)” and “θ_(z)” with respect to thehorizontal direction of the y-axis and z-axis are expressed by thefollowing expressions (3) and (4).

$\begin{matrix}{\theta_{y} = {\sin^{- 1}\frac{a_{y}}{1G}}} & (3) \\{\theta_{2} = {\sin^{- 1}\frac{a_{z}}{1G}}} & (4)\end{matrix}$

The “a_(y)” in the expression (3) is acceleration in the y-axisdirection and “a_(z)” in the expression (4) is acceleration in thez-axis direction.

That is, the inclination calculator 330 calculates the inclinationangles of the x-axis, y-axis, and z-axis with respect to the horizontaldirection by performing computation expressed in the expressions (2) to(4) on the basis of the accelerations “a_(x)”, “a_(y)”, and “a_(z)” inthe x-axis, y-axis, and z-axis directions output from the corrector 320and the gravitational acceleration “1G”.

The inclination calculator 330 may calculate the inclination angle ofeach axis using the gravitational acceleration (1G) set (stored) in theinclinometer 300 in advance. In this case, for a value of thegravitational acceleration which is set in the inclinometer 300, thelatitude at which the inclinometer 300 is used may be taken intoconsideration.

The inclination calculator 330 may calculate gravitational accelerationfrom the acceleration output from the corrector 320. For example, theinclination calculator 330 can calculate the gravitational accelerationby “(a_(x) ²+a_(y) ²+a_(z) ²)^(1/2)”.

4.2. Inertia Measurement Device

FIG. 15 is a diagram illustrating a configuration example of an inertiameasurement device which is an inertial measurement unit (IMU), and is aside view illustrating a partial cross section. FIG. 16 is a blockdiagram of the inertia measurement device. The inertia measurementdevice 400 is an inertia measurement device attached to a vehicle, andincludes a physical quantity sensor device 410 having the same structureas the physical quantity sensor device 200A (200 B) of the embodiment,an angular velocity sensor device 420, an attitude calculator (circuit)430 that calculates an attitude of the vehicle based on an accelerationsignal of the physical quantity sensor device 410 and an angularvelocity signal of the angular velocity sensor device 420, and anexternal output terminal 431 for outputting a signal corresponding tothe attitude calculated by the circuit 430 to the outside, in the innerspace defined by an under case 401 and an upper case 402. The inertiameasurement device 400 may include, for example, a built-in battery, apower supply circuit, a wireless device, and the like.

The circuit 430 is realized by, for example, a general purposeintegrated circuit (IC) or a field programmable gate array (FPGA), andcalculates the attitude of the vehicle to which the inertia measurementdevice 400 is attached from the acceleration signal of the physicalquantity sensor device 410 and the angular velocity signal of theangular velocity sensor device 420, and outputs a signal correspondingto the attitude. The method of measuring the attitude of the vehiclefrom the acceleration and the angular velocity is well known and will beomitted.

According to the inertia measurement device 400 of this embodiment, thephysical quantity sensor device 410 uses the structure of the sensordevice 200A (200B) of this embodiment. For that reason, since accuracyof the acceleration signal, which is the output of the physical quantitysensor device 410, is high, measurement accuracy of the attitude of thevehicle can be improved as compared with the inertia measurement deviceof the related art.

4.3. Structure Monitoring Device

FIG. 17 illustrates a structural health monitoring (SHM) which is astructure monitoring device 500. The structure monitoring device 500 hasthe same structure as the physical quantity sensor device 200A (200B) ofthe embodiment and includes a physical quantity sensor device 510attached to a structure 590 to be monitored. The physical quantitysensor device 510 includes a transmitter 511 that transmits ameasurement signal. The transmitter 511 may be realized as acommunication module and an antenna separate from the physical quantitysensor device 510.

The physical quantity sensor device 510 is connected to, for example, amonitoring computer 570 through a wireless or priority communicationnetwork 580. The monitoring computer 570 includes a receiver 520connected to the physical quantity sensor device 510 through thecommunication network 580 and an inclination calculator 530 forcalculating an inclination angle of the structure 590 based on areception signal of the receiver 520 (see also FIG. 18).

In this embodiment, the inclination calculator 530 is realized by anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or the like mounted on the monitoring computer 570.However, a configuration in which the inclination calculator 530 isrealized by software by performing operation processing on a programstored in an IC memory 531 by a processor such as a central processingunit (CPU) may be adopted. The monitoring computer 570 can receivevarious operation inputs of the operator through a keyboard 540 anddisplay the result of operation processing on a touch panel 550.

According to the structure monitoring device 500 of this embodiment,inclination of the structure 590 is monitored using the physicalquantity sensor device 200A (200B) of this embodiment. For that reason,it is possible to utilize measurement of highly accurate accelerationwhich is an operation effect of the physical quantity sensor device 200A(200B), it is possible to accurately detect the inclination of thestructure 590 to be monitored, and it is possible to improve monitoringquality of the structure 590.

4.4. Vehicle

FIG. 19 is a diagram illustrating a configuration example of a vehicle.In this embodiment, a vehicle 600 is exemplified as a passenger car, buta vehicle type can be appropriately changed. In addition, the vehicle600 may be a small boat, an automatic transporting device, an in-yardtransporting vehicle, a forklift, or the like.

The vehicle 600 includes a physical quantity sensor device 610 havingthe same structure as that of the physical quantity sensor device 200A(200B) of the embodiment and an automatic operation controller(controller) 620 for controlling at least one of acceleration, braking,and steering based on an acceleration signal of the physical quantitysensor device 610, and can switch execution or non-execution of theautomatic operation based on the measurement signal of the physicalquantity sensor device 610.

The controller 620 is realized by an in-vehicle computer. The controller620 is connected to various sensors and controllers such as the physicalquantity sensor device 610, a throttle controller 602, a brakecontroller 604, a steering controller 606, and the like through acommunication network such as an in-vehicle local area network (LAN) sothat signals can be transmitted and received to and from the controller620 and the sensors and controllers and vice versa. Here, a throttlecontroller 602 is a device that controls output of an engine 601. Abrake controller 604 is a device that controls the operation of a brake603. A steering controller 606 is a device that controls the operationof a power steering 605. The types of sensors and controllers connectedto the controller 620 are not limited to these, and can be appropriatelyset.

Then, the controller 620 is a built-in operation device, and performsoperation processing based on the acceleration measurement signal of thephysical quantity sensor device 610 to determine whether the automaticoperation is to be executed or not. When the automatic operation is tobe executed, the controller 620 transmits a control command signal to atleast one of the throttle controller 602, the brake controller 604, andthe steering controller 606, and controls at least one of acceleration,braking, and steering.

The contents of the automatic control can be set appropriately. Forexample, when acceleration measured by the physical quantity sensordevice 610 reaches a threshold value that is considered to cause spin orcorner-out during cornering, control may be performed to prevent spin orcorner-out. When the acceleration measured by the physical quantitysensor device 610 reaches a threshold value which is considered to havea possibility that a sudden forward or backward movement occurs due toan erroneous operation during stop, control may be performed such thatthe throttle is forcibly fully closed and sudden braking is forciblyactivated.

An advanced driver assistance systems (ADAS) locator used for theautomatically operated vehicle 600 illustrated in FIG. 19 includes, inaddition to an inertial sensor including the physical quantity sensordevice 610, a global navigation satellite system (GNSS) receiver, and amap database storing map data. The ADAS locator measures a travelingposition of the vehicle in real time by combining a positioning signalreceived by the GNSS receiver and a measurement result of the inertialsensor. The ADAS locator reads the map data from the map database. Anoutput from the ADAS locator including the physical quantity sensordevice 610 is input to the automatic operation controller 620. Theautomatic operation controller 620 controls at least one ofacceleration, braking, and steering of the vehicle 600 based on theoutput (including a measurement signal from the physical quantity sensordevice 610) from the ADAS locator.

FIG. 20 is a block diagram illustrating a system related to the vehicle600. A switcher 630 switches execution or non-execution of the automaticoperation in the automatic operation controller 620 based on a change inthe output (including change in the measurement signal from the physicalquantity sensor device 610) from the ADAS locator. The switcher 630outputs a signal for switching from execution of the automatic operationto non-execution of the automatic operation to the controller 620, forexample, in a case of abnormality in which measurement capability of thesensor (including the physical quantity sensor device 610) in the ADASlocator is deteriorated.

The global navigation satellite system (GNSS) described above may use aglobal positioning system (GPS) as a satellite positioning system, forexample. Alternatively, one or more of the satellite positioning systemssuch as a European geostationary-satellite navigation overlay service(EGNOS), a quasi zenith satellite system (QZSS), a global navigationsatellite system (GLONASS), GALILEO, a beidou navigation satellitesystem (BeiDou) may be used. A stationary satellite type satellite-basedaugmentation system (SBAS) such as a wide area augmentation system(WAAS) and a European geostationary-satellite navigation overlay service(EGNOS) may be used for at least one of the satellite positioningsystems.

Although the embodiments have been described in detail above, it will beeasily understood by those skilled in the art that many modificationsare possible that do not deviate from the novel matters and effects ofthe present disclosure. Accordingly, all such modifications are includedin the scope of the present disclosure. For example, in thespecification or the drawings, at least once, a term described togetherwith a different term which is a broader or equivalent term can bereplaced with the different term at any point in the specification orthe drawings. Also, all combinations of this embodiment and modificationexamples are included in the scope of the present disclosure. Forexample, in one embodiment, the present disclosure describes a physicalquantity sensor 10 including: a base 20; a movable plate 40 coupled tothe base along a pivot axis L2; a first arm 31 connected to the base 20;a second arm 32 or 33 connected to the base 20; and a physical quantitymeasurement element 60 that has a proximal end attached to the base 20and a distal end attached to the movable plate 40 and measures aphysical quantity caused by stress. Further, the sensor 10 is subdividedinto four quadrants by the pivot axis L2 and a bisector L1 orthogonal tothe axis L2. The four quadrants include: a first quadrant B11 on a firstside (the C2 side) of the axis L2 and a first side (the A2 side) of thebisector L1; a second quadrant B12 on a second side (the C1 side) of theaxis L2 and the first side (the A2 side) of the bisector L1; a thirdquadrant B21 on the first side (the C2 side) of the axis L2 and a secondside (the A1 side) of the bisector L1; and a fourth quadrant B22 on thesecond side (the c1 side) of the axis L2 and the second side (the A1side) of the bisector L1. The first arm 31 is located in the thirdquadrant B21 and is fixed within the third quadrant B21 only at a fixedregion 31A of the first arm 31 which is less than an entire extent ofthe first arm 31. The second arm 32 or 33 is located in at least one ofthe first quadrant B11 and the second quadrant B12 and is fixed withinthe at least one of the first and second quadrants B11, B12 only at afixed region 32A or 33A of the second arm 32 or 33 which is less than anentire extent of the second arm 32 or 33. No fixed region is provided inat least one of the second quadrant B12 and the fourth quadrant B22.

What is claimed is:
 1. A physical quantity sensor comprising: a base; amovable plate coupled to the base along a pivot axis; a first armconnected to the base; a second arm connected to the base; and aphysical quantity measurement element that has a proximal end attachedto the base and a distal end attached to the movable plate and measuresa physical quantity caused by stress, wherein the sensor is subdividedinto four quadrants by the pivot axis and a bisector orthogonal to theaxis, the four quadrants including: a first quadrant on a first side ofthe axis and a first side of the bisector; a second quadrant on a secondside of the axis and the first side of the bisector; a third quadrant onthe first side of the axis and a second side of the bisector; and afourth quadrant on the second side of the axis and the second side ofthe bisector, the first arm is located in the third quadrant and isfixed within the third quadrant only at a fixed region of the first armwhich is less than an entire extent of the first arm, the second arm islocated in at least one of the first quadrant and the second quadrantand is fixed within the at least one of the first and second quadrantsonly at a fixed region of the second arm which is less than an entireextent of the second arm, and no fixed region is provided in at leastone of the second quadrant and the fourth quadrant.
 2. The physicalquantity sensor according to claim 1, wherein the fixed region of thesecond arm is fixed within the second quadrant.
 3. The physical quantitysensor according to claim 1, wherein the fixed region of the second armis fixed within the first quadrant.
 4. The physical quantity sensoraccording to claim 3, further comprising: a third arm connected to thebase, wherein the third arm is located in one of the second quadrant orthe fourth quadrant and is fixed within the one of the second and fourthquadrants only at a fixed region of the third arm which is less than anentire extent of the third arm.
 5. The physical quantity sensoraccording to claim 1, further comprising: a third arm connected to thebase, wherein the third arm is provided with a protrusion on a surfacefacing opposite to a surface to which the physical quantity measurementelement is attached in at least one of the first to fourth quadrantswhere no fixed region is provided.
 6. The physical quantity sensoraccording to claim 1, wherein each fixed region includes a groove filledwith an adhesive.
 7. The physical quantity sensor according to claim 1,wherein the base and the movable portion are coupled via a living hinge.8. The physical quantity sensor according to claim 1, furthercomprising: a device base to which the fixed regions are attached.
 9. Aphysical quantity sensor device comprising: a circuit board; and thethree physical quantity sensors mounted on the circuit board so thateach measurement axis of the three physical quantity sensors is alignedwith each of three orthogonal axes, wherein each of the three physicalquantity sensors includes: a base; a movable plate coupled to the basealong a pivot axis; a first arm connected to the base; a second armconnected to the base; and a physical quantity measurement element thathas a proximal end attached to the base and a distal end attached to themovable plate and measures a physical quantity caused by stress, whereinthe sensor is subdivided into four quadrants by the pivot axis and abisector orthogonal to the axis, the four quadrants including: a firstquadrant on a first side of the axis and a first side of the bisector; asecond quadrant on a second side of the axis and the first side of thebisector; a third quadrant on the first side of the axis and a secondside of the bisector; and a fourth quadrant on the second side of theaxis and the second side of the bisector, the first arm is located inthe third quadrant and is fixed within the third quadrant only at afixed region of the first arm which is less than an entire extent of thefirst arm, the second arm is located in at least one of the firstquadrant and the second quadrant and is fixed within the at least one ofthe first and second quadrants only at a fixed region of the second armwhich is less than an entire extent of the second arm, no fixed regionis provided in at least one of the second quadrant and the fourthquadrant, and a device base is provided to which the fixed regions areattached.
 10. The physical quantity sensor device according to claim 8,wherein the physical quantity is acceleration.
 11. An inclinometercomprising: the physical quantity sensor device according to claim 10;and a calculator that calculates an inclination angle of a structurebased on an output signal from the physical quantity sensor deviceattached to the structure.
 12. A structure monitoring device comprising:the physical quantity sensor device according to claim 10; a receiverthat receives a measurement signal from the physical quantity sensordevice attached to a structure; and a calculator that calculates aninclination angle of the structure based on a signal output from thereceiver.
 13. A physical quantity sensor device comprising: device base;a peripheral wall upstanding from the base; a step transitioning fromthe base to the wall; a physical quantity sensor fixed to the step onlyat select discrete fixed regions, the sensor including: a base elongatedin a first direction; an oscillatable plate pivotally coupled to thebase by a living hinge longitudinally extending in the first direction;a first arm connected to the base independently of the plate; a secondarm connected to the base independently of the plate; and a physicalquantity measurement element having a proximal end attached to the baseand a distal end attached to the plate so as to span the living hinge ina second direction orthogonal to the first direction, wherein the sensoris subdivided into four quadrants by a pivot axis of the living hingeand a longitudinal axis of the physical quantity measurement element,the four quadrants including: a first quadrant on a first side of thepivot axis and a first side of the longitudinal axis; a second quadranton a second side of the pivot axis and the first side of thelongitudinal axis; a third quadrant on the first side of the pivot axisand a second side of the longitudinal axis; and a fourth quadrant on thesecond side of the pivot axis and the second side of the longitudinalaxis, the first arm having a proximal end at the base and extending intothe third quadrant, the first arm including a first one of the discretefixed regions fixed to the step within the third quadrant, the first oneof the discrete fixed regions being less than an entire extent of thefirst arm, the second arm having a proximal end at the base andextending into at least one of the first quadrant and the secondquadrant, the second arm including a second one of the discrete fixedregions fixed to the step within the at least one of the first andsecond quadrants, the second one of the discrete fixed regions beingless than an entire extent of the second arm, and none of the fixedregions is provided in at least one of the second quadrant and thefourth quadrant.
 14. The physical quantity sensor according to claim 13,wherein the second one of the discrete fixed regions is fixed to thestep within the second quadrant.
 15. The physical quantity sensoraccording to claim 13, wherein the second one of the discrete fixedregions is fixed to the step within the first quadrant.
 16. The physicalquantity sensor according to claim 15, further comprising: a third armhaving a proximal end at the base and extending into one of the secondquadrant or the fourth quadrant, the third arm including a third one ofthe discrete fixed regions fixed to the step within the one of thesecond and fourth quadrants, the third one of the discrete fixed regionsbeing less than an entire extent of the third arm.
 17. The physicalquantity sensor according to claim 13, further comprising: a third armthat extends from a proximal end at the base and includes a protrusionabutting against the step within at least one of the first, second, andfourth quadrants where none of the discrete fixed regions is provided.18. The physical quantity sensor according to claim 13, furthercomprising: a third arm that has a proximal end at the base and extendsinto the second quadrant, the third arm including a third one of thediscrete fixed regions fixed to the step within the second quadrant, thethird one of the discrete fixed regions being less than an entire extentof the third arm, wherein the second one of the discrete fixed regionsis fixed to the step within the first quadrant, and none of the fixedregions is provided in the fourth quadrant.
 19. The physical quantitysensor according to claim 13, wherein the second arm has a proximal endat the base and extends into the second quadrant, the second armincluding the second one of the discrete fixed regions fixed to the stepwithin the second quadrant, the second one of the discrete fixed regionsbeing less than an entire extent of the second arm, and none of thefixed regions is provided in the fourth quadrant.
 20. The physicalquantity sensor according to claim 13, wherein the second arm has aproximal end at the base and extends into the first quadrant, the secondarm including the second one of the discrete fixed regions fixed to thestep within the at the first quadrant, the second one of the discretefixed regions being less than an entire extent of the second arm, noneof the fixed regions is provided in the second quadrant, and none of thefixed regions is provided in the fourth quadrant.